Remote power control system with tickle capability

ABSTRACT

An SNMP network comprises a power manager with an SNMP agent in TCP/IP communication over a network with an SNMP network manager. The power manager is connected to control several intelligent power modules each able to independently control the power on/off status of several network appliances. Power-on and load sensors within each intelligent power module are able to report the power status of each network appliance to the SNMP network manager with MIB variables in response to GET commands. Each intelligent power module is equipped with an output that is connected to cause an interrupt signal to the network appliance being controlled. The SNMP network manager is able to test which network appliance is actually responding before any cycling of the power to the corresponding appliance is tried

PRIOR APPLICATIONS

This Application is a continuation of U.S. Patent Application No.11/370,489, filed on Mar. 7, 2006, which is: (1) a continuation of U.S.Pat. No. 7,010,589, issued on Mar. 7, 2006, which is a divisional ofU.S. Pat. No. 6,711,613, issued on Mar. 23, 2004, which is acontinuation-in-part of U.S. Pat. No. 5,949,974, issued on Sep. 7, 1999;(2) a continuation of U.S. Pa. No. 7,099,934, issued on Aug. 29, 2006,which is a continuation-in-part of U.S. Pat. No. 6,711,613, issued onMar. 23, 2004, which is a continuation-in-part of U.S. Pat. No.5,949,974, issued on Sep. 7, 1999; and (3) a continuation of U.S. Pat.No. 7,162,521, issued on Jan. 9, 2007, which is a continuation of U.S.Pat. No. 7,010,589, issued on Mar. 7, 2006, which is a divisional ofU.S. Pat. No. 6,711,613, issued on Mar. 23, 2004, which is acontinuation-in-part of U.S. Pat. No. 5,949,974, issued on Sep. 7, 1999.The contents of all of the listed prior applications are incorporatedherein by reference.

BACKGROUND

1. Field

The technical field relates generally to automatic power control andmore particularly to remote control methods and devices to maintaincomputer network system availability.

2. Description of the Prior Art

Enterprise networks exist to support large world-wide organizations anddepend on a combination of technologies, e.g., data communications,inter-networking equipment (frame relay controllers, asynchronoustransfer mode (ATM) switches, routers, integrated services digitalnetwork (ISDN) controllers, application servers), and network managementapplication software. Such enterprise networks can be used to support alarge company's branch offices throughout the world, and, as such, thesenetworks have become mission critical to the functioning of suchorganizations. Masses of information are routinely expected to beexchanged, and such information exchanges are necessary to carry on thedaily business of modern organizations. For example, some internationalbanks have thousands of branch offices placed throughout Europe, Asiaand the United States that each critically depend on their ability tocommunicate banking transactions quickly and efficiently with oneanother and headquarters.

A typical enterprise network uses building blocks of router and framerelay network appliances mounted in equipment racks. Such equipmentracks are distributed to remote point of presence (POP) locations in theparticular network. Each equipment rack can include frame relaycontrollers, routers, ISDN controllers, servers and modems, etc., eachof which are connected to one or more power sources. The value of POPequipment can range from $200,000 to $500,000, and the number ofindividual devices can exceed a thousand.

Many enterprises rely on an uninterruptible power supply (UPS) to keeptheir network appliances operational. Many network appliances aretypically connected to a single UPS, and this sets up a problem. When anindividual router locks up, the router's power cannot be individuallycycled on and off externally at the UPS because it is connected to amultiple power outlet. The recovery action choices available to thenetwork control center operator thus do not include being able toreinitialize the individual equipment through a power interruptionreset. The network operator could command the UPS to power cycle, butthat would reset all the other attached devices that were ostensiblyoperating normally and carry other network traffic. Another option is todispatch someone to the remote location to reset the locked-up device.Neither choice is an attractive solution.

In large organizations that have come to depend heavily on enterprisenetworks, great pressures develop to control costs and thus to improveprofits. Organizational down-sizing has been used throughout thecorporate world to reduce non-network costs, and that usually translatesto fewer technical people available in the right places to support largeand complex in-house global networks. Such reduced repair staffs nowrely on a combination of centralized network management tools andthird-part maintenance organizations to service their remote POP sites.The Costs associated with dispatching third-party maintenancetechnicians is very high, and the dispatch and travel delay times canhumble the business operations over a wide area for what seems aneternity.

Global communication network operators, located at a few centralizednetwork management centers, are relying more and more automated networkmanagement applications to analyze, process, display and support theirnetworks. An increasing number of network management softwareapplications are being marketed that use open-system standardizedprotocols. Particular network application tool software is available toreport lists of the network appliances, by location, and can issuetrouble lists and keep track of software versions and releases. Newsimple network management protocol (SNMP) applications areconventionally used to issue alarms to central management consoles whenremote network appliances fail.

One such SNMP network management application is marketed byHewlett-Packard. HP OPENVIEW is a family of network and systemmanagement tools and services for local and wide area multivendornetworks. OPENVIEW is a management platform that provides applicationdevelopers and users with the ability to manage multivendor networks andexpand their distributed computing environments. OPENVIEW allows networkoperation centers to build an intelligent hierarchical networkmanagement application, and uses open standards such as SNMP, userdatagram protocol (UDO), and the noew ubiquitous transmission controlprotocol/internet protocol (TCP/IP). Because OPENVIEW is build on opensystem standards, global communication network operators can easilyintegrate the various inter-networking equipment nodes into a managedenvironment operated by strategically located network consoles.

In order to provide a reliable computing environment, a robust andactive process for problem resolution must be in place. OPENVIEW allowsthe definition of thresholds and monitoring intervals, and theinterception of network, system, database, and application-messages andalerts. Once a threshold value is exceeded, intelligent agents can run apre-defined automatic action and/or generate and send a message to alertan operator on a central management console. Messages can also beforwarded to a pager or trouble-ticketing application. To help focus onthe most critical problems, a message browser window is used to displaysix severity levels for incoming problems and events, e.g., ranging fromstable to critical. An integrated history database is provided forauditing and analyzing system and network activities, for identifyingtrends and for anticipating problems before they occur. Activitydisplays and reports can be customized by the users.

Prior art SNMP network management uses embedded microprocessors inalmost every network appliance to support two-way inter-computercommunications with TCP/IP, of which SNMP is a member of the TCP/IPprotocol. SNMP is conventionally used to send messages betweenmanagement client nodes and agent nodes. Management information blocks(MIBs) are used for statistic counters, port status, and otherinformation about routers and other network devices. GET and SETcommands are issued from management consoles and operate on particularMIB variable for the equipment nodes. Such commands allow networkmanagement functions to be carried out between client equipment nodesand management agent nodes.

SNMP is an application protocol for network management services in theinternet protocol suite. SNMP has been adopted by numerous networkequipment vendors as their main or secondary management interface. SNMPdefines a client/server relationship, wherein the client program, a“network manager”, makes virtual connections to a server program, an“SNMP agent”, on a remote network device. The data base controlled bythe SNMP agent is the SNMP management information base, and is astandard set of statistical and control values. SNMP and private MIBsallow the extension of standard values with values specific to aparticular agent. Directives issued by the network manager client to anSNMP agent comprise SNMP variable identifiers, e.g., MIB objectidentifiers or MIB variables, and instructions to either GET the valuefor the identifier, or SET the identifier to a new value. Thus privateMIB variables allow SNMP agents to be customized for specific devices,e.g., network bridges, gateways, and routers. The definitions of MIBvariables being supported by particular agents are located in descriptorfiles, typically written in abstract syntax notation (ASN.1) format. Thedefinitions are available to network management client programs.

SNMP enjoys widespread popularity, and SNMP agents are available fornetwork devices including computers, bridges, modems, and printers. Suchuniversal support promotes interoperability. The SNMP managementprotocol is flexible and extensible, SNMP agents can incorporate devicespecific data. Mechanisms such as ASN.1 files allow the upgrading ofnetwork management client programs to interface with special agentcapabilities. Thus SNMP can take on numerous jobs specific to deviceclasses such as printers, routers, and bridges. A standard mechanism ofnetwork control and monitoring is thus possible.

Unfortunately, SNMP is a complicated protocol to implement, due tocomplex encoding rules, and it is not a particularly efficient protocol.Bandwidth is often wasted with needless information, such as the SNMPversion that is to be transmitted in every SNMP message, and multiplelength and data descriptors scattered throughout each message. SNMPvariables are identified as byte strings, where each byte corresponds toa particular node in the MIB database. Such identification leads toneedlessly large data handles that can consume substantial parts of eachSNMP message.

Most vendors implement network managers thinking a user's primaryinterest is in the data associated with particular network devices. Butsuch data is easily acquired by other means, e.g., “netstat” and “rsh”UNIX programs. The important information about the network includes thedifferences between devices, besides their current states. SNMP affordsgood mechanism for rapidly processing such differences on largenetworks, since SNMP avoids the processing burden of remote login andexecution.

Network management applications can thus monitor the health of everypart of a global communications network and can be set to communicatealarms to a central management console. Current network managementapplications do an adequate job of informing central management consolesabout the health of various nodes in the network and the alarms theyissue when a node is failing are useful.

Conventional SNMP network management technologies do not providesufficient information related to the nodes' electrical power status. Anew technology is needed that can be simply and inexpensively added toclient equipment nodes for SNMP reporting of the electrical power statusof the node. For example, in a router based network with SNMP support,prior art individual routers can use SNMP to issue an alarm to themanagement console. But the console operator would know only that therouter is failing. A GET command can be issued to the router node todetermine if the counter and buffer threshold limits were exceeded andcaused a router to lock-up. However, the console operator does not haveany information about the electrical power status to the router, e.g.,has the router power switch been moved to the OFF position or has theswitch been accidentally turned OFF? The electrical power source couldhave failed the power cable connection become loose, or a technician mayhave accidentally removed the router from a rack.

SUMMARY

Certain embodiments of the present invention provide a system and methodfor providing power supply status and control in network nodes atgeographically distant locations.

Certain embodiments of the present invention provide a system and methodfor describing power supply status and control in SNMP MIB variablebetween network nodes and a central network management console.

Certain embodiments of the present invention provide a verification ofwhich particular network appliance will be subjected to a power-up orpower-down command before the operator must commit to such commands.

Briefly, an SNMP network embodiment of the present invention cancomprise a power manager with an SNMP agent in TCP/IP communication overa network with an SNMP network manager. The power manager can beconnected to control several intelligent power modules each able toindependently control the power on/off status of several networkappliances in an equipment rack at a common remote node, e.g., apoint-of-presence site. Power-on and load sensors within eachintelligent power module can report the power status of each networkappliance to the SNMP network manager with MIB variable in response toGET commands. Each intelligent power module can be equipped with anoutput that is connected to cause an interrupt signal to the networkappliance being controlled. The SNMP network manager can test whichnetwork appliance is actually responding before any cycling of the powerto the corresponding appliance is tried.

An advantage of certain embodiments of the present invention is that asystem and method can be provided that can help an operator avoid themistake of turning on or off the wrong network appliance in a busyequipment rack at a remote site.

Another advantage of certain embodiments of the present invention isthat a system and method can be provided for describing power supplystatus and control in SNMP MIB variables between network nodes and acentral network management console.

A further advantage of certain embodiments of the present invention isthat a system and method can be provided that allows a network consoleoperator to investigate the functionality of the electrical power statuswhen a router or other network device has been detected as failing.

A still further advantage of certain embodiments of the presentinvention is that a system and method can be provided for reducing theneed for enterprise network operators to dispatch third partymaintenance vendors to remote equipment rooms and POP locations simplyto power-cycle failed network appliances. The costs to dispatch suchthird party maintenance vendor can run from $300-$600 per call. The costof implementing the present invention can be recaptured in less than oneyear, e.g., by reducing the number of third party maintenance dispatchesto remote locations.

Another advantage of certain embodiments of the present invention isthat a system and method can be provided for reducing the time it takesto restore a failed network appliance and improving service levelmeasures.

Another advantage of certain embodiments of the present invention isthat a system and method can be provided for reducing organizationlosses from network downtime. Being able to immediately power-cycle afailed server and thus return the server to operation can directlyreduce the downtime loss to the organization.

There are other objects and advantages of various embodiments of thepresent invention. They will no doubt become obvious to those ofordinary skill in the art after having read the following detaileddescription of the preferred embodiments which are illustrated in thevarious drawing figures.

IN THE DRAWINGS

FIG. 1 is a block diagram of a simple network management protocol (SNMP)network embodiment of the present invention;

FIG. 2 is a flowchart of a method of appliance power switch statusdetection, according to the present invention;

FIG. 3 is a schematic of a representative intelligent power module suchas are included in the network of FIG. 1;

FIG. 4 is a schematic diagram of thee load sensor included in theintelligent power module of FIG. 3; and

FIG. 5 is a schematic diagram of the power-on sensor included in theintelligent power module of FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates a simple network management protocol (SNMP) networkembodiment of the present invention, referred to herein by the generalreference numeral 10. The SNMP network 10 includes a host 12 with aTCP/IP connection 14 to a plurality of point-of-presence (POP) nodesrepresented by a pair of network equipment racks 16 and 18. SNMP networkmanagement is provided by a SNMP manager 20 in communication with arespective pair of SNMP agents 22 and 24 at the remote nodes. The SNMPmanager 20 may comprise a commercial product such as IBM NETVIEW/6000,HP OPENVIEW, POLYCENTER, SunNet MANAGER, Cabletron SPECTRUM, etc.

An uninterruptable power supply (UPS) 26 provides operating power to aTCP/IP-addressable enterprise power manager 28. It also powers aplurality of intelligent power modules (IPM's) 30, 32, 34, 36 that areable to switch the operating power on/off to a corresponding networkappliances 38, 40, 42, 44.

An SNMP agent 46 is private to the power manager 28. It does not dependon the equipment rack 16 or any of its network appliances 38, 40, 42,44. The power manager 28 is connected to independently control each ofthe intelligent power modules 30, 32, 34, 36. Such control includesbeing able to sense the power-on and load status of each of the networkappliances 38, 40, 42, 44 and to switch power on and off to each of thenetwork appliances 38, 40, 42, 44. Such status is sensed and reported byan SNMP GET command 48 and the power switching is accomplished with anSNMP SET command 50 that issue from the host 12.

The power manager 28 and IPM's 30, 32, 34, 36, are also able to generatean interrupt signal to each corresponding network appliances 38, 40, 42,44. Although FIG. 1 shows only the four network appliances 38, 40, 42,44, typical installations will have so many that it is easy for thewiring of the power supply to get confused. In practice this hashappened often enough that serious consequences have been paid when thenetwork appliance that was supposed to be controlled by a particular IPMwas not. Given the dependence that customers, users, and suppliers nowplace on the uninterrupted operation of their networks, accidentalinterruptions cannot be tolerated at all.

If the SNMP manager 20 intends, for example, to power cycle the thirdnetwork appliance 42, an interrupt signal is sent to IPM 34 via SNMPagent 46. If IPM 34 really is supplying the power to network appliance42, an interrupt signal will be processed and a message will be sent onthe TCP/IP network 14. Such message will be received by the SNMPappliance 42 as having been “tickled”. If such message does not appear,or it appears and identifies a different network appliance, then thesystem administrator will be alerted to a probable wiring error.

Many commercial network devices provide a contact or logic-level inputport that can be usurped for the “tickle” signal. Cisco Systems routers,for example, provide an input that can be supported in software to issuethe necessary message and identifier to the system administrator. Adevice interrupt has been described here because it demands immediatesystem attention, but a polled input port could also be used.

A network appliance 38, 40, 42, 44, that needs to have its power cycledon/off may need such action to clear a software lockup that hasoccurred. A power-on reset is needed to get the appliance to reboot. Insuch instances, a “tickle” signal from an IPM would be ignored becausethe recipient is essentially dead. Some systems may be temporarilyawakened from their death sleep by a non-maskable interrupt andinterrupt service routine. There may be enough resources to issue themessage and identification that the system administrator needs to see.It will therefore be best for routine checks to be made before there isany trouble to register which IPM 30, 32, 34, 36, matches which networkappliance 38, 40, 42, 44.

If the devices being supplied operating power by the IPM's 30, 32, 34,36, are NT-servers, then an RS-232 serial interface is present that canbe used for the “tickle” signal. In particular, the request-to-send(RTS) control line can be provided with a pulled-up dry-contact oropen-collector from the IPM's 30, 32, 34, 36. A application programinterface (API) is then added to the NT-server to issue the reportmessage and identity when the RTS is toggled.

FIG. 2 shows a method of appliance power switch status detection,referred to herein by the general reference numeral 100. The method 100comprises a step 102 applying a series of alternating current (AC)voltage pulses to an appliance with an on/off switch that aresynchronized to a source of AC power. A step 104 senses the presence ofany series of AC current pulses that result if the appliance switch isclosed. A step 106 analyzes any AC current pulses detected in step 104to determine if they resulted from the application of the AC voltage instep 102. A step 108 outputs an on/off status indication for theappliance switch. Method 100 does not result in the turning-on and theoperation of the appliance during steps 102 or 104, and is thereforeunobtrusive.

FIG. 3 illustrates an intelligent power module 200, similar tointelligent power modules 30, 32, 34, 36, which may be located externalor internal to devices 38, 40, 42, 44, or internal or external to theUPS 26. The intelligent power module 200 includes a power supply andclock generator 212, a load sensor 214, a power-on sensor 216, asolid-state relay 218 and a microprocessor 220. A serial input/output(I/O) connection 221 provides for communication with a controller, e.g.,power manager 28.

A “tickle” relay 222 is controlled by the microprocessor 220 and canissue a dry-contact test signal. Such signal is intended to stimulate amessage and identity report to a system administrator. Preferably, theoperating power is controlled by an IPM and such test signal or “tickle”are wired to the same network appliance.

An appliance, such as the network appliances 38, 40, 42, 44, has a poweron/off switch 223 that may be internal or external to the appliance, andis represented in FIG. 3 by a network device load 224 connected to anetwork 225. The switch 223 may also actually comprise both internal andexternal switches in series. The incoming alternating current (AC) linepower is applied to the intelligent power module 200 at a hot (H)terminal 226, a neutral (N) terminal 227 and a ground (G) terminal 228.The appliance has its incoming AC line power applied to a hot (H)terminal 230, a neutral (N) terminal 232 and a ground (G) terminal 234,which are respectively connected to a hot (H) terminal 236, a neutral(N) terminal 238 and a ground (G) terminal 240. A relay 242 allowsautomatic remote control by the microprocessor of power to the appliancedue to its position in the incoming AC line.

A network monitor 243 and a system administrator are able to receivemessage and identity reports issued by the network device load 224 inresponse to a “tickle” signal.

The load sensor 214 is such that if a current is flowing because switch223 is closed, the microprocessor will receive a logic low statusindication.

FIG. 4 represents an embodiment of the load sensor 214 included in FIG.3. The load sensor 214 comprises a sense resistor 244 connected to avoltage comparator 245. When the voltage dropped across the senseresistor 244 exceeds a reference voltage provided by a power supply 246,the output of the voltage comparator 245 goes high. A resistor 247couples this to an opto-isolator 248 and produces a five volt digitaloutput (I_SENS) that indicates load/no-load to the microprocessor 220. Aresistor 250 provides a pull-up to a current sense input to themicroprocessor 220.

FIG. 5 represents an embodiment of the power-on sensor 216 included inFIG. 3. The power-on sensor 216 includes an opto-isolator 252. Theoutput of the ipto-isolator 252 goes low when a sufficient voltage isdropped across a resistor 254. A five volt power supply connection and apull-up 256 provide a five volt logic output (V_SENS) that indicatespower/no-power to the microprocessor 220.

In operation, the device 200 senses if switch 223 is closed or open byconverting AC current pulses from the power supply 212 that flow throughthe series circuit comprising the solid-state relay 218, the H-terminals230 and 236, the switch 223, the network device load 224, theN-terminals 232 and 238, the load sensor 214, and return to the powersupply 212. If the switch 223 is open, no such current can flow.

The power supply and clock generator 212 provides a five volt pulseclock (CLK) to the microprocessor 220 at each zero-crossing of theincoming AC power line voltage across the H-terminal 226 and theN-terminal 227. A slightly delayed version of the clock is output by themicroprocessor 220 to control the solid-state relay 218. A seventy voltAC output (70VAC) of the power supply and clock generator 212 provides areduced voltage AC sine wave that is approximately seventy volts RMS.The solid-state relay 218 therefore gates through the seventy volt ACwaveform twice each cycle such that alternating pulses of +70 volts and−70 volts are sent through switch 223 and load sensor 214. If a currentflows because the switch 223 is closed, a characteristic pulsesynchronized to the CLK signal will appear as an output from theopto-isolator 248. A resistor 250 provides a pull-up to a current senseinput to the microprocessor 220. If the switch 223 is open, thecharacteristic pulses will not appear. An “on-sense” opto-isolator 252provides isolation for a voltage sense input to the microprocessor 220.

The microprocessor 220 analyzes and stores its determination of whetherthe power is applied to the device 38-44 and whether the switch 223 isclosed. Such data is thereafter useful to control the relay 242. Themicroprocessor 220 is programmed to control the relay 242 and to reportthe presence of current and voltage to the appliance through serialcommunication conducted over the serial I/O connection 221.

The power manager 28 is able to read from the intelligent power modules30, 32, 34, 36, whether there is a proper operating voltage beingsupplied to the network appliances 38, 40, 42, 44, and whether suchloads are turned on. The power manager 28 and its SNMP agent 46 are ableto report such status in response to the GET command 48. The GET commandmodifies a MIB variable that is reported by the SNMP agent 46 to theSNMP manager 20.

The power manager 28 is able to require the intelligent power modules30, 32, 34, 36, to turn the power being supplied to the networkappliances 38, 40, 42, 44, on or off in response to the SET command 50.Such SET commands modify the MIB variable defined for power on/off, andallow independent power-cycling of each and any of the networkappliances 38, 40, 42, 44. Such power cycling promotes a power-up resetof the appliance, e.g., when the SNMP agent 22 has reported a failure ofthe POP node 16 to the SNMP manager 20.

SNMP defines a client/server relationship. The client program, networkmanager 20, makes virtual connections to the server program, the SNMPagent 22 and 24 on a remote network device. The database controlled bythe SNMP agent is the management information base (MIB). The MIB is astandard set of statistical and control values that provides informationabout the attributes of devices attached to the network. SNMP allows forthe extension of these standard values with values that are specific toa particular SNMP agent through the use of private MIBs. The use ofprivate MIB variables allows SNMP agents to be modified for a variety ofdevices, e.g., bridges, hubs, routers and CSU/DSUs, etc. SNMP operatesby exchanging network information through protocol data unit (PDU)messages. PDUs carry variables that have both titles and values. Thereare five types of PDUs that SNMP uses to monitor a network, two forreading terminal data, two for setting terminal data, and one, the trap,monitoring network events. Every SNMP message consists of a variable,and every variable consists of a variable title, the integer, stringdata type of the variable, whether the variable is read-only orread-write, and the value of the variable.

The SNMP manager 20 collects information via MIBs about routers, hubs,bridges, concentrators, servers, switches and other network appliances.When a problem at a remote node is detected, the corresponding SNMPagent issues an alarm that identifies the problem by type and nodeaddress. The SNMP manager typically sends a Telnet script to aTCP/IP-addressable enterprise power manager. The Telnet script instructsthe enterprise power manager to cycle the power cycle, to recover anotherwise locked-up network device. SNMP management is not required forthe enterprise power manger and the associated intelligent powermodules. The intelligent power modules include normally closed relays sopower is always on except when the relay is deliberately opened totrigger a power on reset and reboot. The network management applicationmonitors the UPS and the network appliances.

The load sensor and power-on sensor can be combined such that a consoleoperator can determine if electrical power is available to an equipmentrack and to an individual network appliance. A relay set located betweenthe power source and the client equipment node supports an SNMP-type SETcommand that can be defined to open and close a relay to power-cycle thenetwork appliance. Such power-cycling an clear a lockup condition andallow the device to return to normal operation via its own internalpower-up reset mechanism.

A console operator can be notified by conventional means that a routeris failing. A determination then needs to be made that the electricalpower is available to the equipment rack and to an individual networkappliance. The next action would be to try to power-cycle an individualnetwork appliance to return it to operational status.

A power-on sensor 216, a load sensor 214 and a relay reset 218 can becombined in the electrical power supply connected to the equipment rack.Once a console operator has determined both that the router is failingand that the electrical power is available to the equipment rack and tothe individual network appliance, the next logical step can be topower-cycle the individual network appliance, e.g., to return it tooperational status.

Where the in-place equipment that supplies electrical power for anequipment rack cannot be modified to incorporate the functions of anintelligent power module, the intelligent power module 200 can beconnected in-line between the electrical power source and the equipmentpower receptacle. The intelligent power module provides the necessarypower-on sensor, load sensor, and relay reset circuit functions. Thenetwork management console operator can determine by conventional meansthat a device such as a router is failing. With the present invention itcan be further determined that electrical power is available to anequipment rack and to an individual network appliance, and even that thedevice's power switch is on. The present invention further permits anaction to power-cycle the individual network appliance, to return it tooperational status by forcing a reboot.

A pass-through communication switch is preferably included with powermanager 28 that is installed in the same equipment rack with othernetwork appliances because many network appliances have RS-232 networkmanagement system ports. Such management ports are intended to permitusers to upload new software and to update and inspect configurationtables. A call-pass-through multi-port communications switch allows theinitial communications session with modem RS-232 or TCP/IP to beswitched directly to a device's management port. For example, when acommunications session is established to reboot a locked up router,after the router is back in operation, the same communications sessioncan be transferred from the power manager 28 to the router's managementport. Preferably, such transfer of the particular communications sessioncan be switched directly from a user interface screen in communicationwith the SNMP agent 46. The network operator can thereafter continue therepair operation by inspecting or updating the router's configurationtable, and to verify its operability.

User interfaces are preferably provided to be configured by a systemadministrator at the SNMP manager 20. A screen interface allows anoperator to control individual intelligent power modules 30, 32, 34, 36,directly from an associated keyboard. A command interface preferablyallows script files to be constructed and sent directly for execution.Response codes are returned after each command is executed. Group namesare preferably supported which allows a single command to controlmultiple devices.

The power manager 28 preferably supports a variety of communicationinterfaces, such as, RS-232 and ETHERNET. Out-of-band communications areconnectable through an RS-232 interface using a DB9-type connector on aback panel. Such a port is used to establish communications sessions. Anexternal dial-in-modem can also be used to establish communications.In-band communications are preferably provided with a LAN communicationsinterface that supports ETHERNET connections, e-g., 10BaseT or 10Base2,with both IPX and TCP/IP protocols being supported.

A seven layer network communications model that is universally used tocommunicate between most types of computer networks is defined by theInternational Organization of Standards (ISO). Every layer relies on allits lower layers to complete its communication tasks. There are sevenlayers identified as the application, presentation, session, transport,network, data link, and physical layers. For example, e-mail is a taskof the application layer. The application layer uses all of the layersbelow it to deliver particular e-mail messages to their destinations.The presentation layer formats the look of the e-mail, and the physicallayer actually transports the binary data across the network. For moreinformation, see, Naugle, Matthew G., Local Area Networking,(McGraw-Hill: New York), 1991.

The information that the SNMP manager 20 can gather from the SNMP agents22 and 24 around a network is the definition of the MIB and it has ahierarchical tree structure. At the top of the tree is the generalnetwork information. Each branch of the tree gets more detailed about aspecific network area. The leaves of the tree include the most detail. Adevice may be a parent in the tree, and its children can be discreteserial and parallel devices. Each node in the MIB tree can berepresented by a variable. The top of a local area network MIB tree isusually referred to as “internet”.

Managed objects are accessed via the MIB and are defined using a subsetof ASN.1. Each object type is named by an object identifier, which is anadministratively assigned name. The object type and an object instanceuniquely identify a specific object. Descriptor text strings are used torefer to the object type.

Network information is exchanged with protocol data unit (PDU) messages,which are objects that contain variables and have both titles andvalues. SNMP uses five types of PDUs to monitor a network. Two deal withreading terminal data, two deal with setting terminal data, and one, thetrap, is used for monitoring network events such as terminal start-upsor shut-downs. When a user wants to see if a terminal is attached to thenetwork, for example, SNMP is used to send out a read PDU to thatterminal. If the terminal is attached, the user receives back a PDU witha value “yes, the terminal is attached”. If the terminal was shut off,the user would receive a packet informing them of the shutdown with atrap PDU.

In alternative embodiments of the present invention, it may beadvantageous to include the power manager and intelligent power modulefunctions internally as intrinsic components of an uninterruptable powersupply (UPS). In applications where it is too late to incorporate suchfunctionally, external plug-in assemblies are preferred such thatoff-the-shelf UPS systems can be used.

Although the present invention has been described in terms of thepresent embodiment, it is to be understood that the disclosure is not tobe interpreted as limiting. Various alterations and modifications willno doubt become apparent to those skilled in the art after having readthe above disclosure. Accordingly, it is intended that the appendedclaims be interpreted as covering all alterations and modifications asfall within the true spirit and scope of the invention.

1. A remotely manageable power distribution unit comprising incombination: A. a power strip housing; B. a power input disposed in thepower strip housing; C. a first plurality of power outputs disposed inthe power strip housing, each among the first plurality of power outputsbeing connectable to one or more electrical loads external to the powerstrip housing and connected to a first power input among the pluralityof power inputs; D. a power control section disposed with the powerstrip housing in network communication with a remote power controlsystem and in power controlling communication with one or more of thepower outputs among the first plurality of power outputs; and E. atickle issuance circuit disposed with the power strip housing incommunication with the remote power control system and communicatablewith at least one external equipment unit.
 2. The remotely manageablepower distribution unit of claim 1, wherein the tickle issuance circuitis an external appliance identity testing circuit.
 3. The remotelymanageable power distribution unit of claim 1, wherein the power controlsection comprises one of a power-on sensing circuit, a load sensingcircuit, and a power off circuit.
 4. The remotely manageable powerdistribution unit of claim 2, wherein the power control sectioncomprises one of a power-on sensing circuit, a load sensing circuit, anda power off circuit.
 5. The remotely manageable power distribution unitof claim 1, wherein the power control section comprises two of apower-on sensing circuit, a load sensing circuit, and a power offcircuit.
 6. The remotely manageable power distribution unit of claim 2,wherein the power control section comprises two of a power-on sensingcircuit, a load sensing circuit, and a power off circuit.
 7. Theremotely manageable power distribution unit of claim 1, wherein thepower control section comprises a power-on sensing circuit, a loadsensing circuit, and a power off circuit.
 8. The remotely manageablepower distribution unit of claim 2, wherein the power control sectioncomprises a power-on sensing circuit, a load sensing circuit, and apower off circuit.
 9. The remotely manageable power distribution unit ofclaim 1, wherein the tickle issuance circuit is operable to issue anappliance identity testing signal to any of a plurality of externalequipment units, wherein at least one of the plurality of externalequipment units is mounted in an electrical equipment rack.
 10. Theremotely manageable power distribution unit of claim 2, wherein at leastone external equipment unit is mounted in an electrical equipment rack.11. The remotely manageable power distribution unit of claim 10, whereinthe power strip housing is mounted in an electrical equipment rack. 12.A method of remotely managing power distribution unit, the methodcomprising in combination: A. providing a power distribution unit; B.providing power through the power distribution unit to externalelectrical appliances; C. remotely monitoring the power distributionunit and power information provided by the power distribution unit; andD. issuing a tickle inquiry signal from the power distribution unit toone or more among the external electrical appliances.
 13. The method ofclaim 12, wherein the tickle inquiry signal is an external applianceidentity testing signal.
 14. The method of claim 12 also comprising,with the power distribution unit, sensing power information status of atleast one of the external electrical appliances, wherein the powerinformation status comprises at least one of a power-on status and aload status.
 15. The method of claim 14, further comprisingcommunicating the power information status to a remote network managerthrough an IP connection.
 16. The method of claim 12, furthercomprising, in response to issuing the tickle inquiry signal, sending anidentity report to a network monitor, the identity report comprisinginformation identifying the one or more among the external electricalappliances.
 17. The method of claim 13, further comprising, in responseto issuing the external appliance identity testing signal, sending anidentity report to a network monitor, the identity report comprisinginformation identifying the one or more among the external electricalappliances.
 18. The method of claim 12 also comprising, with the powerdistribution unit, controlling the supply of power to the one or moreamong the external electrical appliances.
 19. The method of claim 12,further comprising, upon receiving an external appliance identityresponse to the tickle inquiry signal, issuing a power-related commandwith respect to one of the one or more among the external appliances,wherein the power-related command comprises one of a power on command, apower off command, and a power cycle command.
 20. The method of claim19, wherein the step of issuing a power-related command comprisesissuing the power-related command to an intelligent power module,wherein the intelligent power module is in operating power communicationwith one of the one or more among the external electrical appliances.21. The method of claim 13, further comprising, upon receiving anexternal appliance identity response to the external appliance identitytesting signal, issuing a power-related command with respect to one ofthe one or more among the external appliances, wherein the power-relatedcommand comprises one of a power on command, a power off command, and apower cycle command.
 22. The method of claim 21, wherein the step ofissuing a power-related command comprises issuing the power-relatedcommand to an intelligent power module, wherein the intelligent powermodule is in operating power communication with one of the one or moreamong the external electrical appliances.
 23. The method of claim 12,further comprising, in response to issuing the tickle inquiry signal,sending a message corresponding to one of the one or more among theexternal electrical appliances to a network monitor and a systemadministrator.
 24. The method of claim 23, wherein the messageidentifies the one of the one or more among the external electricalappliances as having been tickled.
 25. The method of claim 13, furthercomprising, in response to issuing the external appliance identitytesting signal, sending a message corresponding to one of the one ormore among the external electrical appliances to a network monitor and asystem administrator.
 26. The method of claim 25, wherein the messageidentifies the one of the one or more among the external electricalappliances as having been tickled.